1. Technical Field
The present application relates generally to perforating technology, and more specifically to shaped charges including reactive materials.
2. Background Art
To complete a well, one or more formation zones adjacent a wellbore are perforated to allow fluids from the formation zones to flow into the wells for production to the surface or to allow injection fluids to be applied into the formation zones. In a perforation operation, a perforating gun string may be lowered into the wellbore and the guns fired to create openings in the casing and to extend perforations into the surrounding formation.
To produce more hydrocarbons from tight formations, fracturing may be needed to open up these perforations. For example, fracture fluids, which may contain proppants, may be forced with high pressure into the formations to open the fissures. For carbonate formations, acid treatments may be used to achieve the same purpose by dissolving the carbonates. As a result, cracks and pores of the rock around the wellbore are opened up, allowing the formation fluids, e.g., gas, oil, and water, to flow into the wellbore.
FIG. 1 illustrates an embodiment of well treatment system 8, which may include a perforating gun 21, an applicator tool 24, and a surge tool 10. The perforating gun 21 is used to create perforation tunnels 18 in formation 16. The applicator tool 24 may be used to apply treatment fluids (e.g., fracturing fluids or completion fluids) in the perforation tunnels 18. The application of the treatment fluids may be controlled by a timer 23 or other mechanisms.
Perforating gun 21 includes perforating charges 26 that are activatable to create perforation tunnels 18 in formation 16 surrounding a wellbore interval and casing 20. Perforating gun 21 can be activated by various mechanisms, such as by a signal communicated over an electrical conductor, a fiber optic line, a hydraulic control line, or other type of conduit.
Well treatment system 8 may further include an applicator tool 24 for applying a treatment fluid (e.g., acid, chelant, solvent, surfactant, brine, oil, enzyme and so forth, or any combination of the above) into the wellbore 12, which in turn flows into the perforation tunnels 18. The treatment fluid applied can be a matrix treatment fluid. Upon opening of a port 27, the pressurized fluid is communicated into the surrounding wellbore interval.
The surge tool 10 may be used to create a local transient underbalance condition, which will facilitate removal (wash out) debris that may damage the tunnels 18. Surge tool 10 typically contains surge charges, which, when detonated, generate penetrations 25 through the wall of housing 22. The penetrations 25 allow the inside of the surge tool 10 to be in fluid communication with fluids in the wellbore. Because the surge tool 10 has a lower internal pressure than that of the wellbore, it creates a dynamic underbalance when the well fluids flow into the surge tool 10. For description of surge tools, see for example U.S. Pat. No. 7,428,921, issued to Grove et al., the entirety of which is incorporated herein by reference.
In fracturing operations, dynamic overbalance may be desirable for generating deeper and larger perforating tunnels, which would facilitate subsequent fracturing or acid treatment in Sandstone, Carbonate and Coal formations, leading to better production.